Endothelial cells are critical in regenerative medicine for endothelialization of vascular grafts and promoting vasculogenesis in tissue engineered or damaged native tissues. Embryonic stem cells are one potential source for generating endothelial cells for these applications. However, until now only low yields of endothelial cells have been derived from embryonic stem cells using biochemical stimuli. Other factors, such as mechanical forces, that may influence and promote differentiation remain to be investigated. Studies have shown that the application of mechanical forces can affect phenotype and metabolism in a variety of cell types, recently shown in vascular progentior cells as well. Thus, the hypothesis of this proposal is that mechanical forces can direct differentiation of embryonic stem cells towards a mature and functional endothelial phenotype. In order to test this hypothesis murine and human (cell lines BG01 and BG02) embryonic stem cells will be cultured on substrated-coated surfaces and exposed to tensile or shear stresses. [unreadable] [unreadable] [unreadable]